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The National Climate Data Centerr (NCDC) released its computation of average annual temperatures for 2012, and it was the hottest on record. By a lot.

The first graph shows average annual temperature from 1895 to 2012. The solid red line is for the Continental United States, the solid blue line is for Missouri. I’ve added dashed trend lines. First, you can see that the average temperature in Missouri is higher than the national average, by about 2.5°F. I’m not sure why, we’re pretty centrally located.

The year-to-year change in average temperature also tends to be higher for Missouri than nationally. Not surprising; as a single state, Missouri can be influenced by regional weather patterns, while national patterns might be balanced by what’s occurring in different regions. The average yearly difference computes to 0.75°F for the Continental U.S., and to 1.32° for Missouri.

The graph shows that both Missouri and the country were cooler in 1895 than they are now. The state warmed in the 1930s – that corresponds with the dust-bowl era. Then it cooled again in the 1960s and 70s. In about 1980, it started to warm again. Nationally, the period since 2000 has been the hottest on record. Until 2012, Missouri had been warm during the 2000s, but not as warm as the 1930s. Last year shattered records, however, both in Missouri and nationally.

The next graphic shows how hot it was in each state by rank: 118 means it was the hottest year ever recorded, 117 means it was the second hottest, and so forth. Not every state had its hottest year on record, but quite a few did, many of them close to Missouri. Only the State of Washington wasn’t so hot.

Temperature data like this is the very heart of the theory of global warming. Clearly there is a lot of variability in climate year-to-year, and over larger time periods as well. However, the trend is clearly towards higher temperatures, and the question is why that is happening now. This is a period when the physical patterns that control climate (solar cycles, volcanic eruptions, or El Niño, for instance) do not suggest that it should be trending warmer as shown in the data. The theory of global warming due mostly to human emission of greenhouse gas emissions best explains what is happening.

Sources: much of the data on the NCDC website is created dynamically in response to queries entered by each user. Other data, like announcements, changes frequently. The day I did this post, I found the map of statewide ranks on the State of the Climate page, http://www.ncdc.noaa.gov/sotc.